ADC-metal complexes as effective catalysts for hydrosilylation of alkynes

Aminocarbene complexes cis-[PtCl2{C(N(H)N = CR2R3)=N(H)R1}(CNR1)] (7–15) prepared via the nucleophilic addition of hydrazones H2N–N=CR2R3 [R2, R3 = Ph 4; R2/R3 = 9H-fluorenyl 5; R2 = H, R3 = 2-(OH)C6H4 6] to cis-[PtCl2(CNR1)2] [R1 = cyclohexyl (Cy) 1, 2,6-Me2C6H3 (Xyl) 2, 2-Cl-6-MeC6H3 3] were evaluated as catalysts for the hydrosilylation of terminal alkynes with trisubstituted silanes giving vinyl silanes. The optimized catalytic system runs at 80–100 °C in dry toluene for 3–6 h with a typical catalyst loading of 0.1 mol%. A range of substrates with different steric hindrance and activity (Et3SiH, Pr3SiH, iPr3SiH, and PhMe2SiH as silanes; PhCtriple bond; length of mdashCH, tBuCtriple bond; length of mdashCH, and 4-(tBu)C6H4Ctriple bond; length of mdashCH as alkynes) were successfully transformed into the target silylated products in 83–99% yields attesting the versatility of our catalytic system. Decreasing the catalysts loading to 10−3 mol% guaranteed the maximum TONs of 4.0 × 104 and TOFs of 1.7 × 103 (h−1) that were accomplished within 24 h of the reaction.